In recent years, various attempts have been made to treat plantar fasciitis. These approaches have not been particularly successful, and as a consequence have resulted in patients experiencing protracted periods of pain and discomfort. In addition, because of the very limited success of the treatment options available, physicians are unclear as to which option (for example, surgical or non-surgical) to pursue.
Plantar fasciitis is an inflammation of the plantar fascia, a ligament which is attached at one end to the inner tubercle of the heel bone. The plantar fascia extends from the heel bone, becoming broader and thinner as it runs longitudinally along the bottom of the foot, eventually dividing into 5 processes which connect to each of the five toes. There is no clear understanding of the exact cause(s) of inflammation in the plantar fascia. Some data point to the occurrence of heel spurs where the plantar fascia is attached to the calcaneus (heel bone), which themselves may be due to constant stretching of the fascia.
A number of issued patents disclose methods and apparatuses to treat plantar fasciitis by using a biomechanical approach. Generally speaking, the biomechanical methods attempt to position the patient's foot and leg for some period of time (often at night when the patient is asleep) in such a way so as to slightly stretch the plantar fascia, as a means by which the plantar fasciitis may eventually be relieved. For example, Bergmann et al. U.S. Pat. No. 5,776,090, disclose method and device for treating plantar fasciitis by placing a splint on the dorsal aspect of a patient's foot, ankle and foreleg, and holding the patient's foot, toes and ankle in the dorsiflexed position. The inventors state that stretching the patient's plantar fascia reduces symptoms over time.
Stano, U.S. Pat. No. 5,799,659 discloses an ankle foot orthosis night splint for treating plantar fasciitis. The disclosed orthosis is a rigid, molded shell having a generally U-shaped cross-sectional configuration and a flat foot bed. The orthosis is covered by a soft-fabric, and uses a removable and interchangeable foot bed wedge insert which permits the angle of dorsiflexion and the amount of plantarflexion to be varied.
Shipstead, U.S. Pat. No. 5,718,673 discloses foot supporting devices and methods to hold the wearer's foot and leg at a predetermined angle for sufficient time to reduce foot fatigue or pain, while the wearer is not on the feet.
Gleichner, U.S. Pat. No. 4,168,585 discloses a one-piece heel cushion formed of homogeneous elastomeric material adapted to conform to the insole of a wearer's shoe to relieve heel pain. The cushion tapers toward its forward end and has an elongated cavity in the lower surface extending directly under the heel bone.
Fisher et al., U.S. Pat. No. 5,611,153 disclose an insole and a method for relieving bottom of heel pain (i.e., plantar heel pain). The insole, which is removable, is comprised of a flexible, shock-absorbing material, and is tapered downward from the arch portion.
An excellent description of biomechanical and other non-surgical methods for treating plantar fasciitis can be found in the published journal article entitled "Outcome of nonsurgical treatment for plantar fasciitis," by L H Gill and G M Kiebzak, appearing in Foot and Ankle Int, September 1996, Volume 17, Number 9, pages 527-532. The authors report on the use of short leg walking cast, steroid injection, rest, ice, runner's shoe, crepe-soled shoe, aspirin or non-steroidal anti-inflammatory drug, heel cushion, low-profile plastic heel cup and heat, to treat plantar fasciitis. They found that most of the treatments were unpredictable or minimally effective.
Surgical treatments for plantar fasciitis have also been proposed, usually as a last resort, as these methods can have associated with them a variety of complications, including foot numbness, protracted post-operative pain and discomfort, skin incision problems or painful scars on the bottom of the foot. Endoscopic surgery has also been described. For example, McNamara et al., U.S. Pat. No. 5,429,117 disclose a method and system for performing endoscopic surgery at locations where tissue inserts into bone, as for example with the plantar fascia.
Physical therapy based on ultrasound methods have also been used for treatment of plantar fasciitis, with the therapeutic benefits assumed to result from the production of heat within the body. An excellent reference for such techniques can be found in the book Therapeutic Heat and Cold, Fourth Edition, edited by Justus F. Lehmann and published by Williams and Wilkins of Baltimore, Md. in 1990. Although ultrasound based physical therapy is widely used, mostly for deep heating of muscles (to provide relief from the effects associated with spasms) and for relief from joint pain, it apparently has been utilized much less frequently for the treatment of plantar fasciitis, and when it has, little success has been achieved. When prescribed for the treatment of plantar fasciitis, ultrasound therapy is applied by a physical therapist to a patient in a relatively uncontrolled way (i.e., the therapist applies the ultrasound in an ad hoc fashion), at relatively high power intensities (e.g., at or above 1 Watt/cm.sup.2) for short periods (about 5 minutes) only 2-3 times per week at most.
Numerous ultrasound therapy devices have been described. For example, Cody, U.S. Pat. No. 5,558,623 discloses a therapeutic ultrasonic device which transmits multiple ultrasonic frequencies through a single ultrasound applicator. The applicator is hand-held by a specially trained therapist during treatment of a patient at a particular anatomical site, usually at ultrasound spatial-average temporal-average (SATA) intensities of 1 Watt per square centimeter or more. Because of the relatively high intensities used, a "stroking" technique is almost always utilized. A similar device, also applied by a physical therapist, is described by Pohl et al., U.S. Pat. No. 5,578,060, which discloses a reconfigurable physical therapy apparatus and a method of providing operator-selected stimuli to a patient.
Several other ultrasound methods and devices relating primarily to bone growth and repair have also been described. For example, Kaufman et al., U.S. Pat. No. 5,309,808 disclose apparatus and method for therapeutically treating and/or quantitatively evaluating bone tissue in vivo, by subjecting bone to an ultrasonic signal pulse of finite duration, and involving a composite sine-wave signal consisting of plural discrete frequencies. These frequencies are spaced in the ultrasonic region to approximately 2 MHz; the excitation signal is repeated substantially in the range 1 to 1000 Hz. In a closely related patent, Kaufman et al., U.S. Pat. No. 5,458,130, the same inventors extend the apparatus and method to the treatment to musculoskeletal tissue in general. In another patent by the same inventors, Kaufman et al., U.S. Pat. No. 5,547,459 disclose apparatus and method for therapeutically treating bone tissue in vivo, by subjecting bone to an ultrasonic sinusoidal signal pulse peculiarly modulated by a sinusoidal signal with a frequency between about 0 Hz and 25 kHz.
Duarte, U.S. Pat. No. 4,530,360 discloses apparatus and a method of using ultrasonic energy for therapeutic treatment of bone tissue in vivo, using a pulsed sine wave at substantially a single frequency within the range 1.3 to 2.0 MHz, and at a pulse repetition rate of 100 to 1000 Hz.
Talish, U.S. Pat. No. 5,762,616 discloses apparatus for ultrasonic treatment of sites corresponding to the torso. The apparatus includes means for positioning and holding an ultrasound treatment head module adjacent to positions of the body, such as the clavicle, the pelvis and the spine.
The prior art, exemplified by the references that have been briefly discussed, have used either biomechanical, ultrasonic or surgical approaches, for treating plantar fasciitis. The surgical option, while it can sometimes relieve patients of pain, has associated with it various side effects as well as high costs, and is generally chosen only as a last resort. Non-surgical approaches have not as yet been very successful in treating plantar fasciitis. However, the present inventors have discovered how to achieve much greater success with use of a non-surgical method using ultrasound in treating the pain and discomfort associated with plantar fasciitis.